The present invention relates generally to methods and apparatus for the cleaning deposits from the interior of storage tanks. More specifically, the present invention relates to methods and apparatus for attaching a pressure washing device to a storage tank that allows for adjustment of the location of the pressure washing device. More specifically, the preferred embodiments show a light-weight and easily relocatable device that can be transported to or permanently mounted on both stationary and transportable tanks to effect the jet washing of the tank.
In many industries, large storage tanks are commonly used for the storage of liquid products. The liquids stored in such tanks may contain materials that tend to deposit and build up on the interior of the tank. It is not uncommon to have several inches of material deposited before the tank is taken out of service for cleaning.
Storage tanks that are used for storing fluids used in the drilling of hydrocarbon wells are particularly susceptible to the build up of solids within the tanks. Drilling fluids are normally very dense fluids that have a high solids content. These solids will tend to settle out of the fluid and deposit within the storage tanks. This solid material can be very thick and difficult to remove from the tank.
In applications where the material in the tank is non-hazardous, the tank would normally be cleaned by personnel entering the tank through an access port, or manway, and manually cleaning the tank. These personnel may utilize suction hoses, hand-held pressure washers, shovels, and other tools, but the process has traditionally been a highly labor intensive endeavor.
One automated technique for cleaning storage tanks utilizes a programmable pressure washer that can be permanently mounted to the tank shell, or inserted through a permanently installed fitting. These systems usually include a rotating washer head that is provided with one or more nozzles that are moved automatically to make the wash head cover a specified area. These pressure washers are normally adapted to be installed in a fixed position relative to the tank with the wash head providing all the movement required.
In general, the tank geometry, including any internal obstructions, and the distribution of deposits make it difficult to match the washing pattern of a single washing head to a specific tank configuration because with the types of washing systems described above, usually some areas are more intensely washed than others. Further, so-called “shadowe” areas that are shielded from the direct impact of the jet by pipe, stanchions, baffles and the like, are not well cleaned. Therefore, many of the systems described above employ several washing heads simultaneously and may operate for extended periods of time, such that excess consumption of washing liquid may occur. This excess consumption of washing liquid represents a poor exploitation of time, an increased energy cost, possibly an undesired wear on the tank interior, and it involves an increased cost of purifying the waste liquid which is discharged in larger quantities than may be necessary. Further, in many cases, access is limited to a manway or other large openings in the tank, and nozzles positioned only at these locations cannot completely clean tanks with shadowed areas.
Thus, there remains a need in the art for methods and apparatus to improve the efficiency of tank washing systems. The embodiments of the present invention are directed to methods and apparatus for adjustably mounting a pressure washing system to any tank that needs to be cleaned, particularly those with internal shadowing elements. The embodiments include a system that can be permanently mounted or that is capable of being transported and put into place without the use of mechanical lifting equipment, thus overcoming the limitations of the prior art.